JP2021184376A - Protective device - Google Patents

Abstract

To provide protective devices having small capacitance differences among individuals, and having less influence in signal degradation.SOLUTION: A protective device 30 includes an insulator layer 7 with a first cavity 1 and a second cavity 2, a first element 21, and a second element 22. The first element 21 includes a pair of first electrodes 40 mutually opposing through the first cavity 1. The second element 22 includes a pair of second electrodes 41 mutually opposing through the second cavity 2. The first element 21 causes discharge in the first cavity 1 if voltage across the first electrodes 40 reaches a discharge voltage. The second element 22 causes discharge in the second cavity 2 if voltage across the second electrodes 41 reaches a discharge voltage.SELECTED DRAWING: Figure 2

Description

The present disclosure relates generally to protective devices, and more particularly to protective devices with discharge cavities.

Conventionally, a protective device as a surge absorber is known (see Patent Document 1).

In the surge absorber of Patent Document 1, the first and second pair of internal electrodes and a part of the first and second pair of internal electrodes are arranged so as to be exposed inside the insulator block (ceramic element). In the surge absorber provided with the discharge cavity, a dummy cavity for stress relaxation is arranged in the vicinity of the discharge cavity. When one side in the direction perpendicular to the main surface of the internal electrode is the upper side and the other side is the lower side, the dummy cavity is placed on the upper or lower side of the discharge cavity or on the upper and lower sides via the insulator layer. Arrange on both sides. In addition, the dummy cavity is positioned substantially coaxially with the discharge cavity.

Japanese Unexamined Patent Publication No. 2007-227259

On the other hand, when two conventional protection devices are used in the same circuit, if a protection device having a large difference in capacitance is used, there is a problem that the signal waveform is blunted and the signal waveform is deteriorated.

The present disclosure has been made in view of the above problems, and an object of the present invention is to provide a protective device having a small difference in individual capacitance and a small influence on signal deterioration.

The protective device according to one aspect of the present disclosure has a first cavity and a second cavity in the insulating layer, and includes a first element and a second element. The first element has a pair of first electrodes facing each other through the first cavity. The second element has a pair of second electrodes facing each other via the second cavity. The first element causes a discharge in the first cavity when the voltage between the pair of first electrodes reaches the discharge voltage. The second element causes a discharge in the second cavity when the voltage between the pair of second electrodes reaches the discharge voltage.

According to the present disclosure, it is possible to provide a protective device having a small difference in individual capacitance and a small influence on signal deterioration.

FIG. 1 is a diagram illustrating a function of an ESD suppressor according to an embodiment. FIG. 2 is an exploded perspective view of the same ESD suppressor. FIG. 3 is a diagram illustrating a configuration of a circuit using the same ESD suppressor. FIG. 4A is a signal waveform of one element of the same ESD suppressor. FIG. 4B is a signal waveform of the other element of the same ESD suppressor. FIG. 4C is a differential signal of FIGS. 4A and 4B of the same ESD suppressor. FIG. 5A is a signal waveform of one of the elements when the capacitance difference of the elements of the same ESD suppressor is large. FIG. 5B is a signal waveform of the other element of the same ESD suppressor. FIG. 5C is a differential signal between FIGS. 5A and 5B of the same ESD suppressor. FIG. 6 is a confirmation signal using an oscilloscope in the circuit configuration using the same ESD suppressor. FIG. 7A is an eye diagram when the same ESD suppressor is used. FIG. 7B is an eye diagram when the ESD suppressor is not used.

The embodiments and modifications described below are merely examples of the present disclosure, and the present disclosure is not limited to the embodiments and modifications. Other than the following embodiments and modifications, various changes can be made according to the design and the like as long as they do not deviate from the technical idea of the present disclosure.

Further, "identical" in the present embodiment includes an exact match and a range of manufacturing error (for example, less than ± 10%).

(Embodiment)
Hereinafter, the protective device 30 according to the present embodiment will be described with reference to FIGS. 1 to 7B.

(1) Overview For high-speed interface peripheral devices and electronic devices such as mobile phones and smartphones, protective devices such as varistor and surge absorber are used as measures against static electricity (ESD: Electro-Static Discharge). Differential signal transmission is used in high-speed interface peripherals. Differential signal transmission is the transmission of a signal by the potential difference between two signal lines.

The protection device 30 according to the present embodiment is an ESD suppressor that protects parts vulnerable to ESD from ESD. In the following description, the protective device 30 will be described as an ESD suppressor 30.

As shown in FIGS. 1 to 3, the ESD suppressor 30 includes a first element 21, a second element 22, and an insulating layer 7. The first element 21 has a third electrode 3, a fourth electrode 4, and a first cavity 1. Further, the second element 22 has a fifth electrode 5, a sixth electrode 6, and a second cavity 2. The first cavity 1 and the second cavity 2 are formed in the same insulating layer 7. That is, the insulating layer 7 has a first cavity 1 and a second cavity 2.

As shown in FIG. 2, the ESD suppressor 30 includes a first insulating layer block 14 in which an insulating layer 8, an insulating layer 9, and an insulating layer 10 are laminated, an insulating layer 11, an insulating layer 12, and an insulating layer. A second insulating layer block 15 in which the 13 is laminated is further provided.

The first element 21 causes a discharge in the first cavity 1 between the third electrode 3 and the fourth electrode 4 when the potential difference between the third electrode 3 and the fourth electrode 4 reaches the discharge voltage. Let me. The first element 21 causes a discharge in the first cavity 1 to bypass the current due to the ESD to the ground (GND), and protects the protection target such as an IC (Integrated Circuit) from the ESD.

The second element 22 causes a discharge in the second cavity 2 between the fifth electrode 5 and the sixth electrode 6 when the potential difference between the fifth electrode 5 and the sixth electrode 6 reaches the discharge voltage. Let me. The second element 22 causes a discharge in the second cavity 2 to bypass the current due to the ESD to the ground (GND), and protects a protected object such as an IC (Integrated Circuit) from the ESD.

As shown in FIG. 3, the ESD suppressor 30 is connected between the interface (IF) circuit 20 and the common mode choke coil (CMCC) 23. Specifically, one end of the first element 21 is connected to the signal line on the outward path from the IF circuit 20 to the CAN transceiver (Controller Area Network-Transceiver) 24. The other end of the first element 21 is grounded. One end of the second element 22 is connected to the signal line on the return path from the CAN transceiver 24 to the IF circuit 20. The other end of the second element 22 is grounded.

The CAN transceiver is a CAN standard transmitter / receiver. CAN is a type of serial communication protocol. Microcontrollers and devices can be connected without using a CAN standard host computer.

The common mode choke coil 23 is a filter that reduces common mode noise. The common mode choke coil 23 separates signals and noise depending on the transmission mode. There are two types of transmission modes, a differential mode and a common mode, and in principle, the differential mode is used for the signal. The common mode choke coil 23 is a filter that acts only on the common mode, and reduces the common mode noise generated in the common mode without affecting the differential mode which is a high-speed signal.

Regarding the influence of connecting the ESD suppressor 30 to the circuit as the protection device 30, signal confirmation with an oscilloscope (see FIG. 6) and signal evaluation by an eye diagram are carried out. In signal confirmation with an oscilloscope, the input signal is divided into a signal component and a noise component, and it is evaluated whether they are output.

In the eye diagram, in the circuit shown in FIG. 3, the signal from the IF circuit 20 and the signal on the CAN transceiver 24 side are connected. An eye diagram is a graphical display of these inputs and outputs sampled and superimposed. In the eye diagram, the opening area inside the eye diagram can be evaluated, and the period and voltage can also be evaluated.

(2) Configuration As shown in FIGS. 1 to 3, the ESD suppressor 30 of the present embodiment includes two ESD suppressors, a first element 21 and a second element 22, in the ESD suppressor 30. The first element 21 includes a first cavity 1, a third electrode 3, and a fourth electrode 4. The second element 22 includes a second cavity 2, a fifth electrode 5, and a sixth electrode 6.

As shown in FIG. 2, the ESD suppressor 30 includes a first insulating layer block 14 in which an insulating layer 8, an insulating layer 9, and an insulating layer 10 are laminated, an insulating layer 11, an insulating layer 12, and an insulating layer. A second insulating layer block 15 in which the 13 is laminated is further provided.

The first insulating layer block 14 and the second insulating layer block 15 isolate the first element 21 and the second element 22 in which ESD discharge is generated from the surroundings, and maintain an electrically insulated state.

The first cavity 1 and the second cavity 2 are cavities formed in the same insulating layer 7. Therefore, the first element 21 and the second element 22 share the thickness of the insulating layer 7. Further, in the insulating layer 7, the first cavity 1 and the second cavity 2 are provided in different regions.

The cavities of the first cavity 1 and the second cavity 2 have a structure in which air or an inert gas is sealed. In this embodiment, it will be described as a structure in which air is enclosed.

A pair of first electrodes 40 are provided via the first cavity 1. Specifically, the third electrode 3 of the pair of electrodes 40 is provided on one surface (hereinafter, the first surface) of the two surfaces facing each other in the thickness direction of the insulating layer 7. More specifically, when the insulating layer 7 is viewed from the thickness direction of the insulating layer 7, a part of the third electrode 3 overlaps with the first cavity 1, and at least a part of the remaining parts is the first. It is in contact with (overlaps) the surface of. The remaining part overlaps with the first cavity 1. Of the pair of electrodes 40, the fourth electrode 4 is provided on the other surface (hereinafter, the second surface) of the two surfaces facing each other in the thickness direction of the insulating layer 7. More specifically, when the insulating layer 7 is viewed from the thickness direction of the insulating layer 7, a part of the fourth electrode 4 overlaps with the first cavity 1, and at least a part of the remaining parts is the second. It is in contact with (overlaps) the surface of. The remaining part overlaps with the first cavity 1.

A pair of second electrodes 41 are provided via the second cavity 2. Specifically, the fifth electrode 5 of the pair of electrodes 41 is provided on the first surface of the two surfaces facing each other in the thickness direction of the insulating layer 7. More specifically, when the insulating layer 7 is viewed from the thickness direction of the insulating layer 7, a part of the fifth electrode 5 overlaps with the second cavity 2, and at least a part of the remaining parts is the first. At least a part of the remaining part that is in contact with (overlaps) the surface of the second cavity 2 overlaps with the second cavity 2. Of the pair of electrodes 40, the sixth electrode 6 is provided on the second surface of the two surfaces facing each other in the thickness direction of the insulating layer 7. More specifically, when the insulating layer 7 is viewed from the thickness direction of the insulating layer 7, a part of the sixth electrode 6 overlaps with the second cavity 2, and at least a part of the remaining parts is the second. It is in contact with (overlaps) the surface of. The remaining part overlaps with the second cavity 2. Next, the electrodes will be described. The first element 21 includes a third electrode 3 and a fourth electrode 4. The third electrode 3 and the fourth electrode 4 form a pair of first electrodes 40.

The second element 22 includes a fifth electrode 5 and a sixth electrode 6. The fifth electrode 5 and the sixth electrode 6 form a pair of second electrodes 41.

The pair of first electrodes 40 and the pair of second electrodes 41 have the same shape. That is, the third electrode 3, the fourth electrode 4, the fifth electrode 5, and the sixth electrode 6 have the same shape.

The orientation along the longitudinal direction in the shape of the pair of first electrodes 40 and the orientation along the longitudinal direction in the shape of the pair of second electrodes are the same direction. That is, the pair of first electrodes 40 and the pair of second electrodes 41 are arranged along the same direction. Further, the third electrode 3, the fourth electrode 4, the fifth electrode 5, and the sixth electrode 6 are oriented in the same direction along their respective longitudinal directions.

Since the third electrode 3 and the fourth electrode 4 face each other via the first cavity 1, the distance between the pair of first electrodes 40 is the thickness of the first cavity 1. On the other hand, since the fifth electrode 5 and the sixth electrode 6 face each other via the second cavity 2, the distance between the pair of second electrodes 41 is the thickness of the second cavity 2. Since the first cavity 1 and the second cavity 2 are cavities formed in the insulating layer 7, the first cavity 1 and the second cavity 2 have the same thickness as the insulating layer 7. That is, the distance between the pair of first electrodes 40 and the pair of second electrodes 41 is the same.

The pair of first electrodes 40 have an area where the third electrode 3 and the fourth electrode 4 overlap in the direction in which the first insulating layer block 14 is viewed from the second insulating layer block 15. That is, the pair of first electrodes 40 have facing areas (see FIG. 1). Further, the pair of second electrodes 41 also have an area where the fifth electrode 5 and the sixth electrode 6 overlap in the direction in which the first insulating layer block 14 is viewed from the second insulating layer block 15. That is, the pair of second electrodes 41 have facing areas.

Assuming that the permittivity is ε, the area of the facing electrodes is S, the distance between the facing electrodes is d, and the capacitance of the space is C, the capacitance C is generally expressed by the following equation.
C = ε ・ S / d

Since air is sealed in the first cavity 1 and the second cavity 2, it can be considered that the dielectric constants ε of the first element 21 and the second element 22 are the same.

The pair of first electrodes 40 and the pair of second electrodes 41 have overlapping areas in the facing electrodes, and when the areas are the same, the first element 21 and the second element are derived from Equation 1. It can be said that the capacitance with 22 is the same.

In the present embodiment, the two protective elements, the first element 21 and the second element 22, are used as an ESD suppressor 30 in which two elements of the same lot with little variation during manufacturing are combined into one body. ..

The manufacturing method of the ESD suppressor 30 of this embodiment will be described. First, an insulating sheet is formed in order to form the insulating layers 8 to 10. By laminating the insulating sheets, the insulating layer block 14 in which the insulating layers 8 to 10 are laminated is formed.

Next, the third electrode 3 and the fifth electrode 5 are formed on the surface of the insulating layer block 14 by a screen printing method. In the screen printing method, the screen mask is aligned with the insulating layer block 14. Ink is applied to the mask and the mask pattern is transferred to the surface of the insulating layer block 14 using a squeegee. Although the difference in the amount of misalignment varies from lot to lot, the difference in the amount of misalignment in the same lot is smaller than the difference in the amount of misalignment from lot to lot.

After that, the insulating layer 7 is formed by a screen printing method. Specifically, the third electrode 3 and the fifth electrode 5 are formed on the surface of the insulating layer block 14, and the insulating layer 7 is formed on the third electrode 3 and the fifth electrode 5 by a screen printing method. The insulating layer 7 has a first cavity 1 and a second cavity 2. A material for forming the cavity is embedded in the region forming the first cavity 1 and the second cavity 2. In the screen printing method, the amount of misalignment between the first cavity 1 and the third electrode 3 and the amount of misalignment between the second cavity 2 and the fifth electrode 5 in order to align and form the insulating layer 7. , Have the same amount of deviation if they are in the same lot.

Next, the fourth electrode 4 and the sixth electrode 6 are formed by a screen printing method. In screen printing that forms the 4th electrode 4 and the 6th electrode 6, the masks are aligned and installed. Therefore, if the lot is the same, the amount of misalignment that forms the 4th electrode 4 and the 6th electrode 6 is large. , The amount of misalignment is smaller than that of different lots.

After that, the insulating sheet is laminated so as to cover the insulating layer 7, the fourth electrode 4, and the sixth electrode 6. Specifically, the insulating layers 11 to 13 are laminated to form the insulating layer block 15. From the above, the prototype of the ESD suppressor 30 is completed.

Next, the ESD suppressor 30 is completed by baking the prototype of the ESD suppressor 30 at a high temperature while applying pressure. By baking at a high temperature while applying pressure, the material for forming the first cavity 1 and the second cavity 2 disappears, and the first cavity 1 and the second cavity 2 are formed.

The first element 21 and the second element 22 of the ESD suppressor 30 formed by the screen printing method are the third electrode 3 and the fifth electrode 5, the first cavity 1 and the second cavity 2, the fourth electrode and the first. The 6 electrodes 6 are produced in the same lot, and the amount of misalignment, the direction of misalignment, and the like are the same. Further, the insulating layer 7 is common. From these facts, the difference in capacitance between the first element 21 and the second element 22 is very small, and it is smaller than the case where the first element 21 and the second element 22 are produced in different lots.

Therefore, the performance difference between the first element 21 and the second element 22 produced in the same lot is smaller than that in the case of producing them in different lots. From the above, the ESD suppressor 30 of the present embodiment has a first element 21 and a second element 22 having a small capacitance difference.

(3) Operation Next, the operation will be described.

As shown in FIG. 3, the ESD suppressor 30 is connected between the IF circuit 20 and the CMCC (Common Mode Choke Coil) 23. The CMCC 23 is connected to the CAN transceiver 24.

In a circuit using differential signal transmission, two signal lines face each other by reverse transmission, and the signal can be taken out by the difference between the two signal lines. The first signal line 25 and the third signal line 27 are the outbound signal lines, and the second signal line 26 and the fourth signal line 28 are the inbound signal lines.

On the outward route, signals are transmitted in the order of IF20, first signal line 25, CMCC23, third signal line 27, and CAN transceiver 24.

On the return route, signals are transmitted in the order of the CAN transceiver 24, the fourth signal line 28, the CMCC23, the second signal line 26, and the IF20.

When ESD occurs in the IF 20, the current due to the ESD flows through the first signal line 25 to the first element 21 of the ESD suppressor 30. When the voltage difference between the electrodes of the pair of first electrodes 40 reaches the discharge voltage, a discharge is generated in the first cavity 1 to protect the circuits of the CMCC 23 and the CAN transceiver 24 from ESD.

On the other hand, when the current due to ESD flows through the second signal line 26, it flows through the second element 22 of the ESD suppressor 30. When the voltage difference between the electrodes of the pair of second electrodes 41 reaches the discharge voltage, a discharge is generated in the second cavity 2 to protect the circuits of the CMCC 23 and the CAN transceiver 24 from ESD.

FIG. 4A shows a graph a showing the correlation between the voltage and time of the first signal line 25, and FIG. 4B shows a graph b showing the correlation between the voltage and time of the second signal line 26.

As shown in FIGS. 4A and 4B, when the capacitance of the first element 21 of the ESD suppressor 30 and the capacitance of the second element 22 are the same, the graph a of FIG. 4A and the graph of FIG. 4B b is almost the same. Therefore, as shown in the graph c of FIG. 4C, the difference between the first signal line 25 and the second signal line 26 becomes equal to 0, and the influence on the differential signal is suppressed. That is, by aligning the capacitances of the first element 21 and the second element 22 of the ESD suppressor 30, the influence on the differential signal can be suppressed. Therefore, it is possible to provide a protective device in which the individual capacitance difference is small and the influence on signal deterioration is small.

A specific signal waveform is shown in FIG. In FIG. 6, in the circuit shown in FIG. 3, the differential mode signal input as a signal component is shown as graph i, the common mode signal as noise component is shown as graph j, and the signal received by the CAN transceiver 24 is shown as graph k.

When the ESD suppressor 30 is used, although there is a common mode which is a noise component, as shown in the graph j of FIG. 6, it is possible to keep the amplitude within a certain range. Therefore, the CAN transceiver 24 can detect the signal component as shown in the graph k by passing through the CMCC 23.

The eye diagram at this time is shown in FIG. 7A. Graph L of FIG. 7A is an eye diagram of a circuit including the ESD suppressor 30 shown in FIG. 3, and graph M of FIG. 7B is an eye diagram of a circuit excluding the ESD suppressor 30 from the circuit shown in FIG. Comparing FIGS. 7A and 7B, there is no difference in the period and voltage of the eye diagram. Therefore, the ESD suppressor 30 does not block the signal and can be applied as a protective device 30.

(4) Advantages A case where there is a remarkable difference between the capacitance of the first element 21 and the capacitance of the second element 22 of the ESD suppressor 30 will be described.

FIG. 5A shows a graph d showing the correlation between the voltage and time of the first signal line 25, and FIG. 4B shows a graph e showing the correlation between the voltage and time of the second signal line 26.

As shown in FIGS. 5A and 5B, when there is a large difference between the capacitance of the first element 21 and the capacitance of the second element 22 of the ESD suppressor 30, graph d of FIG. 5A and FIG. 5B are shown. There is a difference in size from the graph e. Therefore, the difference between the first signal line 25 and the second signal line 26 does not become 0 and remains differential, as shown in graphs f, g, and h of FIG. 5C, for example. The generated signal component is superimposed on the signal component as a noise component.

Therefore, when there is a significant difference between the capacitance of the first element 21 of the ESD suppressor 30 and the capacitance of the second element 22, the ESD suppressor 30 becomes a factor of generating noise.

Therefore, the protection device 30 of the present embodiment has a first cavity 1 and a second cavity 2, and includes a first element 21 and a second element 22. The first element 21 has a pair of first electrodes 40 facing each other through the first cavity 1. The second element 22 has a pair of second electrodes 41 facing each other via the second cavity 2. The first element 21 causes a discharge in the first cavity 1 when the voltage between the first electrodes 40 reaches the discharge voltage. The second element 22 causes a discharge in the second cavity 2 when the voltage between the second electrodes 41 reaches the discharge voltage.

According to this configuration, as described above, the differential signal is almost zero. Therefore, it is possible to provide a protective device in which the individual capacitance difference is small and the influence on signal deterioration is small.

Further, by eliminating the difference in capacitance between the first element 21 and the second element 22 of the ESD suppressor 30, the factors that hinder the signal transmission of the first signal line 25, the second signal line 26, etc. are reduced. Can be done.

(5) Modification examples The modification examples are listed below. The modifications described below can be applied in combination with the above embodiments as appropriate.

In the embodiment, the ESD suppressor 30 has a configuration having two elements, a first element 21 and a second element 22, but is not limited to this configuration. For example, the number of elements may be three or more. For example, the number of elements may be three, and two of the three elements may be selectively used. Further, the number of elements may be one.

In the embodiment, the first cavity 1 and the second cavity 2 of the ESD suppressor 30 are configured to contain air, but the configuration is not limited to this. For example, an inert gas may be encapsulated. Further, it may be filled with a dielectric.

In the embodiment, the method for manufacturing the ESD suppressor 30 is configured to use a screen printing method, but the present invention is not limited to this configuration. For example, it may be manufactured using a hoop material. At the time of manufacturing, they are connected by a hoop material, and in order to stack and manufacture the materials in the connected state, the distance between the electrodes and the overlapping area are determined by the thickness of the coating material or the like. Therefore, in the case of the same lot, if the overlapping area is deviated, all the lots are deviated, so that the ESD suppressor 30 having the same performance difference between the first element 21 and the second element 22 is formed.

In the embodiment, the method for manufacturing the ESD suppressor 30 is configured to use a screen printing method, but the present invention is not limited to this configuration. It may be manufactured by crimping necessary members such as the first insulating layer block 14, the second insulating layer block 15, and the insulating layer 7.

In the embodiment, the ESD suppressor has one differential and one common, and has a first element 21 and a second element 22, but is not limited to this configuration. A plurality of ESD suppressors may be connected in series to the common.

In the embodiment, the first element 21 and the second element 22 of the ESD suppressor 30 are configured to be provided in different regions of the insulating layer 7, but the configuration is not limited to this. The first element 21 and the second element 22 of the ESD suppressor 30 may be provided in the same region of the insulating layer 7. That is, the first cavity 1 and the second cavity 2 may be connected to each other.

(summary)
As described above, the protective device (30) according to the first aspect has the first cavity (1) and the second cavity (2) in the insulating layer (7), and the first element (21). And a second element (22). The first element (21) has a pair of first electrodes (40) facing each other via the first cavity (1). The second element (22) has a pair of second electrodes (41) facing each other via the second cavity (2). The first element (21) causes a discharge in the first cavity (1) when the voltage between the pair of first electrodes (40) reaches the discharge voltage. The second element (22) causes a discharge in the second cavity (2) when the voltage between the pair of second electrodes (41) reaches the discharge voltage.

According to this configuration, it is possible to provide a protective device in which the individual capacitance difference is small and the influence on signal deterioration is small.

In the protective device (30) according to the second aspect, in the first aspect, the first cavity (1) and the second cavity (2) are formed in the same insulating layer.

According to this configuration, the difference in the thickness of the insulating layer (7) between the first element (21) and the second element (22) can be reduced. Therefore, the difference in capacitance between the first element (21) and the second element (22) of the ESD suppressor (30) can be reduced.

In the protective device (30) according to the third aspect, in the first or second aspect, the first cavity (1) and the second cavity (2) are provided in different regions in the insulating layer (7). There is.

According to this configuration, the first element (21) and the second element (22) are formed in different regions of the same insulating layer (7), so that the first element (21) and the second element (22) are formed. ) And the possibility of problems in the electrical insulation state can be suppressed.

In the protective device (30) according to the fourth aspect, in any one of the first to third aspects, the orientation along the longitudinal direction in the shape of the pair of first electrodes (40) and the pair of second electrodes ( The orientation along the longitudinal direction in the shape of 41) is the same direction.

According to this configuration, the orientation along the longitudinal direction in the shape of the pair of first electrodes (40) and the orientation along the longitudinal direction in the shape of the pair of second electrodes (41) are the same. , The difference in capacitance between the first element (21) and the second element (22) can be suppressed.

In the protective device (30) according to the fifth aspect, in any one of the first to fourth aspects, the shape of the pair of first electrodes (40) and the shape of the pair of second electrodes (41) are different. , Is the same.

According to this configuration, if the shapes are the same, it is easy to unify the facing areas, and it is possible to suppress the capacitance difference between the first element (21) and the second element (22) of the ESD suppressor (30). can.

In the protective device (30) according to the sixth aspect, in any one of the first to fifth aspects, the distance between the pair of first electrodes (40) and the distance between the pair of second electrodes (41) are different. , Is the same.

According to this configuration, it is possible to suppress the capacitance difference between the first element (21) and the second element (22). Since the interval has an effect in inverse proportion to the capacitance, it has an effect of reducing the capacitance difference between the first element (21) and the second element (22) of the ESD suppressor (30).

In the protective device (30) according to the seventh aspect, in any one of the first to sixth aspects, the pair of the first electrodes (40) and the pair of the second electrodes (41) are the pair. The overlapping area of the first electrode (40) when viewed from the opposite direction is the same as the overlapping area of the pair of second electrodes (41) when viewed from the opposite direction.

According to this configuration, the size of the overlapping area is proportional to the size of the capacitance. Therefore, by making the overlapping area the same, the capacitance difference between the first element (21) and the second element (22). Can be suppressed.

1 1st cavity 2 2nd cavity 7 Insulation layer 21 1st element 22 2nd element 30 Protective device

Claims (7)

The insulating layer has a first cavity and a second cavity,
A first element having a pair of first electrodes facing each other through the first cavity,
A second element having a pair of second electrodes facing each other through the second cavity.
The first element causes a discharge in the first cavity when the voltage between the pair of first electrodes reaches the discharge voltage.
The second element causes a discharge in the second cavity when the voltage between the pair of second electrodes reaches the discharge voltage.
Protective device. The first cavity and the second cavity are formed in the same insulating layer.
The protective device according to claim 1. The protective device according to claim 1 or 2, wherein the first cavity and the second cavity are provided in different regions in the insulating layer. The orientation along the longitudinal direction in the shape of the pair of first electrodes and the orientation along the longitudinal direction in the shape of the pair of second electrodes are the same direction.
The protective device according to any one of claims 1 to 3. The shape of the pair of first electrodes and the shape of the pair of second electrodes are the same.
The protective device according to any one of claims 1 to 4. The distance between the pair of first electrodes and the distance between the pair of second electrodes are the same.
The protective device according to any one of claims 1 to 5. In the pair of first electrodes and the pair of second electrodes, the overlapping area of the pair of first electrodes when viewed from the opposite direction and the overlapping area of the pair of second electrodes when viewed from the opposite direction are defined. Is the same,
The protective device according to any one of claims 1 to 6.

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